*Article* **Development of DLC-Coated Solid SiAlON/TiN Ceramic End Mills for Nickel Alloy Machining: Problems and Prospects**

**Sergey N. Grigoriev, Marina A. Volosova \*, Sergey V. Fedorov, Anna A. Okunkova , Petr M. Pivkin, Pavel Y. Peretyagin and Artem Ershov**

> Department of High-Efficiency Processing Technologies, Moscow State University of Technology "STANKIN", Vadkovskiy per. 3A, 127055 Moscow, Russia; s.grigoriev@stankin.ru (S.N.G.); sv.fedorov@stankin.ru (S.V.F.); a.okunkova@stankin.ru (A.A.O.); p.pivkin@stankin.ru (P.M.P.); p.peretyagin@stankin.ru (P.Y.P.); a.ershov@stankin.ru (A.E.)

**\*** Correspondence: m.volosova@stankin.ru; Tel.: +7-916-308-49-00

**Abstract:** The study is devoted to the development and testing of technological principles for the manufacture of solid end mills from ceramics based on a powder composition of α-SiAlON, β-SiAlON, and TiN additives, including spark plasma sintering powder composition, diamond sharpening of sintered ceramic blanks for shaping the cutting part of mills and deposition of antifriction Si-containing diamond-like carbon (DLC) coatings in the final stage. A rational relationship between the components of the powder composition at spark plasma sintering was established. The influence of optimum temperature, which is the most critical sintering parameter, on ceramic samples' basic physical and mechanical properties was investigated. DLC coatings' role in changing the surface properties of ceramics based on SiAlON, such as microrelief, friction coefficient, et cetera, was studied. A comparative analysis of the efficiency of two tool options, such as developed samples of experimental mills made of SiAlON/TiN and commercial samples ceramic mills based on SiAlON, doped with stabilizing additives containing Yb when processing nickel alloys (NiCr20TiAl alloy was used as an example). DLC coatings' contribution to the quantitative indicators of the durability of ceramic mills and the surface quality of machined products made of nickel alloy is shown.

**Keywords:** diamond-like carbon coating; high-speed milling; nickel alloy; SiAlON; spark plasma sintering; roughness; wear resistance
